The homogeneity and luminescence properties of undoped bulk GaSb have been studied by the cathodoluminescence (CL) technique in the scanning electron microscope. CL images have revealed a nonuniform distribution of native defects in GaSb wafers prepared from as‐grown single crystals. Postgrowth annealing in vacuum, gallium, and antimony atmospheres has been performed to obtain more accurate information about the defect structure in this material. In general, on annealing, homogeneous distribution of impurities is observed throughout the wafers. CL spectra show that a luminescence band (centered at 756 meV) is enhanced by annealing in a gallium atmosphere, suggesting that Ga atoms play an important role in the formation of this acceptor center. The 756 meV peak has been attributed to a transition from conduction band to an acceptor center comprised of GaSbor a related complex. Interestingly, localized crystallization at the subgrain boundaries seems to occur by annealing in Ga atmosphere. ©1995 American Institute of Physics.